Polycarbonate resin composition and molded article

ABSTRACT

According to the present invention, there are provided a polycarbonate resin composition which comprises (A) 40 to 92 wt % of an aromatic polycarbonate resin (component “a”), (B) 5 to 40 wt % of a styrene-based resin (component “b”), (C) 3 to 20 wt % of a phosphate-based flame retardant (component “c”), and (D) 0.1 to 30 parts by weight of a silicate filler (component “d”) based on 100 parts by weight of the total of the components “a”, “b” and “c”, and which has a chlorine compound content in terms of chlorine atoms of 100 ppm or less as well as a molded product thereof. 
     The resin composition of the present invention can provide a molded product having excellent resistance to wet heat and flame retardancy.

DETAILED DESCRIPTION OF THE INVENTION

1. Field of the Invention

The present invention relates to a polycarbonate resin compositionhaving excellent resistance to wet heat and to a molded product of thesame. More specifically, it relates to a polycarbonate resin compositionwhich is excellent in resistance to wet heat and further in flameretardancy and to a molded product of the same.

2. Related Art

Polycarbonate resins are widely used in the industrial field becausethey have excellent mechanical properties and thermal properties.However, since they are inferior in workability and moldability, a largenumber of polymer alloys of the polycarbonate resins and otherthermoplastic resins have been developed. Out of these, polymer alloysof the polycarbonate resins and styrene-based resins typified by ABSresin are widely used in the fields of automobiles, OA equipment,electronic and electric appliances, and the like. To meet recent strongdemand for flame retardant resin molded products mainly from the fieldsof OA equipment and home electric appliances, a large number of studieson the flame retardation of polymer alloys of the polycarbonate resinsand ABS resin are under way.

Heretofore, a halogen-based flame retardant having bromine and a flameretardant aid such as antimony trioxide have generally been used incombination in the above polymer alloys. However, to cope with such aproblem as the generation of a harmful substance at the time ofcombustion, studies on flame retardation without using a halogen-basedcompound having bromine are now being made energetically. For example,there are now proposed a method of blending triphenyl phosphate andpolytetrafluoroethylene having fibril formability into a polymer alloyof a polycarbonate resin and ABS resin (JP-A 2-32154) (the term “JP-A”as used herein means an “unexamined published Japanese patentapplication”), a method of blending a phosphate-based oligomer which isa condensation phosphoric ester (JP-A 2-115262), a method of blending aspecific inorganic filler and a specific impact modifier (JP-A7-126510), and the like. Meanwhile, great importance is being attachedto performance retainability in long-term use from the viewpoints ofproduct safety, a reduction in the load of environment due to theextension of the service life of a product and product quality warrantedby manufacturers.

However, a polycarbonate resin composition comprising a phosphate-basedflame retardant has such a problem that when it is used for a long time,the blended phosphate-based flame retardant is hydrolyzed and thehydrolyzed product promotes the hydrolysis of the carbonate bonds of apolycarbonate resin, thereby greatly reducing impact strength and thelike. That is, it has been desired to improve the wet heat resistance ofa resin composition prepared by blending a phosphate-based flameretardant into a polymer alloy of a polycarbonate resin and ABS resinand a quick solution to this has been awaited.

SUMMARY OF THE INVENTION

It is a first object of the present invention to provide a polycarbonateresin composition prepared by blending a phosphate-based flame retardantinto a polymer alloy of a polycarbonate resin and a styrene-based resin,which has excellent resistance to wet heat.

It is a second object of the present invention to provide apolycarbonate resin composition prepared by blending a phosphate-basedflame retardant and polytetrafluoroethylene having fibril formability asa drip-proof agent into a polymer alloy of a polycarbonate resin and astyrene-based resin, which is excellent in resistance to wet heat,impact resistance, flame retardancy and coloring.

It is a third object of the present invention to provide a polycarbonateresin molded article which attains V-0 rating in an UL standard 94Vflammability test and rarely experiences reductions in impact strengthand molecular weight under such conditions as relatively hightemperature and high humidity.

The inventor of the present invention conducted studies to attain theabove objects of the present invention and found that a polycarbonateresin composition having excellent flame retardancy and also long-termresistance to hydrolysis (resistance to wet heat) is obtained bycontrolling the content of a chlorine compound in the composition belowa specific value and blending a specific type of inorganic filler when aphosphate-based flame retardant is blended into a polymer alloy of apolycarbonate resin and a styrene-based resin. Thus, the presentinvention was accomplished based on this finding.

According to the present invention, firstly, the above objects andadvantages of the present invention are attained by a polycarbonateresin composition (may be referred to as “resin composition-I”hereinafter) which comprises:

(A) 40 to 92 wt % of an aromatic polycarbonate resin (component “a”);

(B) 5 to 40 wt % of a styrene-based resin (component “b”);

(C) 3 to 20 wt % of a phosphate-based flame retardant (component “c”);and

(D) 0.1 to 30 parts by weight of a silicate filler (component “d”) basedon 100 parts by weight of the total of the components “a”, “b” and “c”,and

which has a chlorine compound content in terms of chlorine atoms of 100ppm or less.

Secondly, the above objects and advantages of the present invention areattained by a polycarbonate resin composition (may be referred to as“resin composition-II” hereinafter) which comprises:

(A) 40 to 92 wt % of an aromatic polycarbonate resin (component “a”);

(B) 5 to 40 wt % of a styrene-based resin (component “b”);

(C) 3 to 20 wt % of a phosphate-based flame retardant (component “c”);

(D) 0.1 to 30 parts by weight of a silicate filler (component “d”) basedon 100 parts by weight of the total of the components “a”, “b” and “c”;

(E) 0.1 to 2 parts by weight of polytetrafluoroethylene (component “e”)having fibril formability based on 100 parts by weight of the total ofthe components “a”, “b” and “c”; and

(F) 1 to 10 parts by weight of a (meth)acrylate-based core-shell graftcopolymer (component “f-1”) based on 100 parts by weight of the total ofthe components “a”, “b” and “c”, and

which has a chlorine compound content in terms of chlorine atoms of 100ppm or less.

The term “resin composition” in the present invention generally refersto both the resin composition-I and the resin composition-II.

The present invention provides a resin composition which has improvedresistance to wet heat (resistance to hydrolysis) and experiences anextremely small reduction in impact strength during its long-term use bycontrolling the content of a chlorine compound to 100 ppm or less interms of chlorine atoms and blending a specific amount of a silicatefiller into a resin composition which comprises a polycarbonate resin,styrene-based;resin and phosphate-based flame retardant.

The polycarbonate resin composition of the present invention will bedescribed in detail hereinunder.

A description is first given of each of the components constituting theresin composition.

(A) Polycarbonate Resin (Component “a”)

The polycarbonate resin which is the component “a” in the presentinvention is a polycarbonate resin obtained by reacting a diphenol witha carbonate precursor, namely, an aromatic polycarbonate resin. Typicalexamples of the diphenol used herein include2,2-bis(4-hydroxyphenyl)propane (to be referred to as “bisphenol A”hereinafter), 1,1-bis(4-hydroxyphenyl)ethane,1,1-bis(4-hydroxyphenyl)cyclohexane,2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane,2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)sulfide,bis(4-hydroxyphenyl)sulfone and the like. The diphenol is preferably a2,2-bis(4-hydroxyphenyl)alkane, particularly preferably bisphenol A. Thecarbonate precursor is a carbonyl halide, carbonic acid diester,bishaloformate or the like. Illustrative examples of the carbonateprecursor include phosgene, diphenyl carbonate, dibischloroformates ofdiphenols and the like. For the production of a polycarbonate resin byreacting the above diphenol with the carbonate precursor, the diphenolsmay be used alone or in combination of two or more and the polycarbonateresin may be a mixture of two or more polycarbonate resins.

The molecular weight of the polycarbonate resin is generally 10,000 to40,000, preferably 12,000 to 30,000 in terms of viscosity averagemolecular weight. The viscosity average molecular weight (M) is obtainedby inserting a specific viscosity (ηsp) obtained from a solutioncontaining 0.7 g of a polycarbonate resin dissolved in 100 ml ofmethylene chloride at 20° C. into the following equation.

ηsp/C=[η]+0.45×[η]² C

[η]=1.23×10⁻⁴M^(0.83) ([η] represents an intrinsic viscosity and Crepresents a polymer concentration)

A brief description is given of an interfacial polymerization method(solution method) for the production of the polycarbonate resin. In theinterfacial polymerization method in which phosgene is used as thecarbonate precursor, a reaction is generally carried out in the presenceof an acid binder and an organic solvent. Examples of the acid binderinclude alkali metal hydroxides such as sodium hydroxide and potassiumhydroxide and amine compounds such as pyridine. Examples of the organicsolvent include hydrocarbon halides such as methylene chloride andchlorobenzene. A catalyst such as a tertiary amine or quaternaryammonium salt may be used to promote the reaction. It is desirable touse a terminal capping agent such as phenol, an alkyl-substituted phenolexemplified by p-tert-butylphenol or aralkyl-substituted phenolexemplified by 4-(2-phenylisopropyl)phenol as a molecular weightmodifier. The reaction temperature is generally 0 to 40° C., thereaction time is 10 minutes to 5 hours, and pH during the reaction ispreferably maintained at 9 or more. All of the molecular chain terminalsthus obtained do not need to have a structure derived from the terminalcapping agent.

An ester interchange reaction (melt polymerization) using a carbonicacid diester as the carbonate precursor is carried out by stirring apredetermined amount of a diphenol component and a branching agent asrequired together with a carbonic acid diester under heating in an inertgas atmosphere and distilling the formed alcohol or phenol. Although thereaction temperature differs according to the boiling point of theformed alcohol or phenol, it is generally in the range of 120 to 350° C.The reaction is started at a reduced pressure and completed while theformed alcohol or phenol is distilled. To promote the reaction, acatalyst used for a known ester exchange reaction, such as an alkalimetal compound or nitrogen-containing basic compound may be used.Illustrative examples of the carbonic acid diester used in the aboveester exchange reaction include diphenyl carbonate, dinaphthylcarbonate, bis(diphenyl)carbonate, dimethyl carbonate, diethylcarbonate, dibutyl carbonate and the like. Out of these, diphenylcarbonate is particularly preferred. It is preferred that a terminalcapping agent such as diphenyl carbonate or methyl(2-15phenyloxycarbonyloxy)benzene carboxylate should be added in the initialstage or intermediate stage of the reaction and a conventionally knowncatalyst deactivator should be added right before the end of thereaction.

The polycarbonate resin which is the component “a” used in the presentinvention may be produced by either one of interfacial polymerizationand melt polymerization. However, the present invention is suited when apolycarbonate resin produced by interfacial polymerization is used asthe component “a”. The reason for this is as follows. As describedabove, a chlorine compound such as a solvent and a modified productthereof, catalyst, catalyst deactivator and modified products thereofand a reaction by-product remain in a polycarbonate resin produced byinterfacial polymerization in no small quantities. The residual chlorinecompound is removed to some degree by purification but it is inevitablethat a trace amount of the chlorine compound remains in thepolycarbonate resin. The present inventor considered that a chlorinecompound mainly derived from a polycarbonate resin and a phosphoricester (component “c”) as a flame retardant contained in the compositioninteract with each other to cause the hydrolysis of the composition.However, the present invention makes it possible to greatly suppress thehydrolysis and improve resistance to wet heat by further blending asilicate filler even when a chlorine compound is existent in somemeasure due to a polycarbonate resin containing the residual chlorinecompound. To suppress the content of a chlorine compound in thecomposition so as to further improve resistance to wet heat, the contentof the chlorine compound in the polycarbonate resin as the mainingredient was reduced. As a result, it was found that the content ofthe chlorine compound in the resin composition should be reduced to 100ppm or less, preferably 90 ppm or less, particularly preferably 50 ppmor less in terms of chlorine atoms.

The content of the chlorine compound in the composition of the presentinvention may be maintained at the above range and the chlorine compoundmay be derived from any component. As described above, however, thepolycarbonate resin (component “a”) is the major ingredient of the resincomposition of the present invention and has the residural chlorinecompound due to the production method of the resin composition.Therefore, a polycarbonate resin having a small content of a chlorinecompound should be used.

The preferable content of a chlorine compound in the polycarbonate resinused which depends on the proportion of the polycarbonate resin(component “a”) to the composition of the present invention and thecontent of a chlorine compound in other components is 100 ppm or less,preferably 90 ppm or less, particularly preferably 20 ppm or less interms of chlorine atoms.

A polycarbonate resin having a low content of a chlorine compound can beobtained by conventionally known methods such as one in which apolycarbonate resin is treated with acetone, one in which elimination ofthe chlorine compound is carried out by forcedly injecting water into anintermediate portion of a vented extruder to pelletize polycarbonateresin powders, one in which a polycarbonate resin solution isprecipitated with a none solvent, one in which a dry treatment isintensified, and the like.

Further, a method of producing polycarbonate resin granules from anorganic solvent solution of a polycarbonate resin by continuouslysupplying the organic solvent solution of the polycarbonate resin into avessel containing polycarbonate resin granules and hot water underagitation and evaporating the solvent, in which the temperature in thevessel is maintained at T₁(°C.) or T₂(°C.) shown in the followingequation, the agitation speed is 60 to 100 rpm, and the agitationcapability is 5 to 10 kw/h·m³, can be preferably used to obtain apolycarbonate resin which has a low content of the residual chlorinecompound, a low content of powders and excellent filtrability anddryability.

0.0018×M ₁+37≦T ₁(°C.)≦ 0.001 ×M ₁+42

(M₁: viscosity average molecular weight of 10,000 to 20,000)

0.0007×M ₂+59≦T ₂(° C.)≦0.0007×M ₂+64

(M₂: viscosity average molecular

The content of chlorine atoms in the polycarbonate resin composition ofthe present invention is measured by a fluorescence X-ray analyticalmethod using the PIX-2000 fully automatic fluorescence X-ray analyzer ofRikagaku Denki Kogyo Co., Ltd.

(B) Styrene-based Resin (Component “b”)

The styrene-based resin used as the component “b” in the presentinvention contains 20 wt % or more, preferably 25 wt % of astyrene-based monomer of styrene, α-methylstyrene or vinyltoluene basedon 100 wt % of the resin. Therefore, the styrene-based resin is ahomopolymer of a styrene-based monomer, a copolymer of styrene-basedmonomers, or a copolymer of a styrene monomer and a vinyl monomer suchas acrylonitrile and methyl methacrylate. Further, the styrene-basedresin may be a polymer obtained by graft polymerizing a rubber componentsuch as a diene-based rubber such as polybutadiene,ethylene.propylene-based rubber, acrylic rubber or composite rubber:having such a structure that a polyorganosiloxane component and apoly(meth)alkyl acrylate component are entangled with each other so thatthey cannot be separated from each other with a styrene-based monomer,or a styrene-based monomer and a vinyl monomer. Illustrative examples ofthe styrene-based resin include resins such as polystyrene, high-impactpolystyrene (HIPS), acrylonitrile.styrene copolymer (AS resin)acrylonitrile.butadiene.styrene copolymer (ABS resin), methylmethacrylate.butadiene.styrene copolymer (MBS resin), methylmethacrylate.acrylonitrile.butadiene.styrene copolymer (MABS resin),acrylonitrile.acrylic rubber.styrene copolymer (AAS resin) andacrylonitrile.ethylene propylene-based rubber.styrene copolymer (AESresin); and mixtures thereof. A styrene-based monomer component iscontained in the copolymer or mixture thereof in an amount of 20 wt % ormore based on 100 wt % of the styrene-based resin. The polymers may beproduced by bulk polymerization, suspension polymerization, emulsionpolymerization, bulk-suspension polymerization, and copolymerization maybe carried out in one stage or multiple stages.

Out of these, the component “b” of the present invention is preferablypolystyrene, high-impact polystyrene (HIPS), acrylonitrile.styrenecopolymer (AS resin) or acrylonitrile.butadiene.styrene copolymer (ABSresin), the most preferably ABS resin from the viewpoint of impactresistance. Further, resins produced by bulk polymerization arepreferably used because they can improve resistance to et heat. Thesecomponents “b” may be used alone or in admixture of two or more.

ABS resin as the component “b” of the present invention is athermoplastic graft copolymer which is obtained by graft polymerizing adiene-based rubber component with a vinyl cyanide compound and anaromatic vinyl compound and usually forms a mixture with other polymerby-produced during the graft polymerization of AS resin or the like. TheABS resin mixed with an AS resin which has been polymerized separatefrom the ABS resin is widely used for industrial purposes. Thediene-based rubber component forming the ABS resin is a rubber having aglass transition point of 10° C. or less, such as polybutadiene,polyisoprene or styrene-butadiene copolymer and preferably used in anamount of 5 to 75 wt % based on 100 wt % of the ABS resin component. Thevinyl cyanide compound to be graft polymerized with the diene-basedrubber component is acrylonitrile, methacrylonitrile or the like. Thearomatic vinyl compound to be graft polymerized with the diene-basedrubber component is styrene, α-methylstyrene or nucleus-substitutedstyrene. As for the contents of the vinyl cyanide compound and thearomatic vinyl compound, the vinyl cyanide compound is contained in anamount of 5 to 50 wt % and the aromatic vinyl compound is contained inan amount of 50 to 95 wt % based on 100 wt % of the total of the vinylcyanide compound and the aromatic vinyl compound. Methyl acrylate,methyl methacrylate, ethyl acrylate, maleic anhydride or N-substitutedmaleimide may be mixed and should be contained an amount of 15 wt % orless in the component “b”.

ABS resin may be produced by any one of bulk polymerization, suspensionpolymerization and emulsion polymerization. As described above, ABSresin produced by bulk polymerization is preferred because it canimprove resistance to wet heat well. The reason for this is yet to beelucidated completely but there is conceivable a possibility that themetal salt component of an emulsifier used for emulsion polymerizationor suspension polymerization exerts a direct influence upon hydrolysiscaused by a phosphoric ester or that the metal salt component acts on achlorine compound remaining in the polycarbonate resin composition toinfluence hydrolysis.

It has been found from studies conducted by the present inventor thatwhen a styrene-based resin (especially ABS resin) containingacrylonitrile as a monomer constituting unit is the component “b”, aresin having a small content of acrylonitrile monomer remaining in theresin is preferred. That is, it has been discovered that when anacrylonitrile monomer derived from the component “b” is contained in theresin composition of the present invention in an amount of more than 50ppm, it exerts an undesired influence upon the wet heat resistance ofthe resin composition. The reason for this is unknown but it is presumedthat the acrylonitrile monomer acts on a phosphoric ester (component“c”) or a chlorine compound contained in the resin to influence thehydrolysis of the polycarbonate resin.

The preferable content of the acrylonitrile monomer in the resincomposition of the present invention is 50 ppm or less, preferably 30ppm or less, the most preferably 20 ppm or less.

In order to reduce the content of the acrylonitrile monomer in the resincomposition to the above level, it is the most simplest means to use aresin having a small content of an acrylonitrile monomer as thestyrene-based resin (especially ABS resin) containing acrylonitrile as amonomer constituent unit. The preferable content of the acrylonitrilemonomer in the component “b”, which is mainly affected by the amount ofthe component “b” in the resin composition, is preferably 200 ppm orless, more preferably 100 ppm or less, particularly preferably 50 ppm orless. When the amount of the residual acrylonitrile monomer satisfiesthe above range, the content of the acrylonitrile monomer in the resincomposition can be controlled to the above range and more excellentresistance to wet heat can be obtained. Therefore, the styrene-basedresin (especially ABS resin) containing acrylonitrile as a monomerconstituent unit is preferably a resin having an acrylonitrile monomercontent of 200 ppm or less, more preferably 100 ppm or less,particularly preferably 50 ppm or less and produced by bulkpolymerization.

(C) Phosphate-based Flame Retardant (Component “c”)

The resin composition of the present invention contains aphosphate-based flame retardant to achieve high flame retardancy withoutcontaining a halogen-containing flame retardant. This component “c” maybe a phosphate-based flame retardant used as a halogen-free flameretardant for a polycarbonate resin.

A preferred phosphate-based flame retardant is represented by thefollowing formula (1):

wherein X is the residual group of an aromatic dihydroxy compound, J, k,l and m are each independently 0 or 1, n is 0 or an integer of 1 to 5,and R₁, R₂, R₃ and R₄ are each independently the residual group of anaromatic monohydroxy compound.

In the above formula (1), j, k, l and m are each independently 0 or 1,preferably all 1. n is 0 or an integer of 1 to 5, preferably 0 or aninteger of 1 to 3, particularly preferably 0 or 1. n is generally givenas the average value of a mixture of an “n” number of phosphates.Therefore, n is 0 to 5, preferably 0 to 3 as the average value. X is theresidual group of an aromatic dihydroxy compound, and R₁, R₂, R₃ and R₄are each independently the residual group of an aromatic monohydroxycompound. The residual group is a group obtained by removing two OHgroups or one OH group from the dihydroxy compound or the monohydroxycompound. For example, the residual group of bisphenol A (X) isrepresented by the following formula.

Examples of X include the residual groups of hydroquinone, resorcinol,bis(4-hydroxydiphenyl)methane, bisphenol A, dihydroxydiphenyl,dihydroxynaphthalene, bis(4-hydroxyphenyl)sulfone,bis(4-hydroxyphenyl)ketone and bis(4-hydroxyphenyl)sulfide. Out ofthese, X is preferably the residual group of hydroquinone, resorcinol orbisphenol A. Examples of R₁, R₂, R₃ and R₄ include the residual groupsof phenol, cresol, xylenol, isopropylphenol, butylphenol andp-cumylphenol. Out of these, the residual groups of phenol, cresol andxylenol are preferred and the residual groups of phenol and xylenol areparticularly preferred.

The phosphate-based flame retardant as the component “c” is preferably amonophosphate compound such as triphenyl phosphate or a condensedphosphoric ester such as resorcinol bis(dixylenylphosphate) because theyhave excellent flame retardancy and excellent flowability at the time ofmolding.

(D) Silicate Filler (Component “d”)

The silicate filler as the component “d” in the present invention is aninorganic filler containing SiO₂ in an amount of 35 wt % or more,preferably 40 wt % or more in its chemical composition. Illustrativeexamples of the silicate filler include kaolin, talc, clay, pyrophylite,mica, montmorillonite, bentonite, wollastonite, sepiolite, xonotlite,natural silica, synthetic silica, glass fillers, zeolite, diatomaceousearth, halloysite, and mixtures thereof.

Out of these, talc, mica, wollastonite and mixtures thereof arepreferred because they are finely dispersed in the resin composition ofthe present invention to increase the number of function points forsuppressing hydrolysis and their effect of reinforcing a resin is alsoimportant to provide flame retardant. Talc is the most preferred.

Mica as the component “d” is preferably powdery with an average particlediameter of 1 to 80 μm to secure a reinforcing effect. Mica is a groundproduct of a silicate mineral containing aluminum, potassium, magnesium,sodium, iron and the like. Mica includes muscovite, phlogopite, biotite,artificial mica and the like. Any one of these may be used but muscovitehaving a high content of SiO2 is more preferred than phlogopite, biotiteand artificial mica obtained by substituting the OH group of phlogopiteby an F atom. Milling methods for the production of mica are a drymilling method in which a mica ore is ground with a dry mill and a wetmilling method in which a mica ore is ground with a dry mill, water isadded to the ground mica to prepare a slurry, and the slurry was thenground with a wet mill, dehydrated and dried. Although the dry millingmethod is more inexpensive and general, it is difficult to grind micathinly and finely. Therefore, mica produced by the wet milling method ispreferably used in the present invention.

The average particle diameter of mica measured by a microtrack laserdiffraction method is preferably 1 to 80 μm. The average particlediameter is more preferably 2 to 50 μm. When the average particlediameter is 1 to 80 μm, a favorable effect is given to flame retardancyand excellent resistance to wet heat can be maintained because finedispersion conditions in the resin are satisfied.

The thickness of mica observed by an electron microscope is 0.01 to 1μm. The thickness is preferably 0.03 to 0.3 μm. Mica may be surfacetreated with a silane coupling agent or the like and granulated with abinder such as an epoxy-based, urethane-based or acryl-based binder.Illustrative examples of the mica include mica powders A-41, A-21 andA-11 manufactured by Yamaguchi Unmo Kogyosho Co., Ltd. They areavailable on the market.

Talc as the component “d” is preferably powdery with an average particlediameter of 0.5 to 20 μm to secure rigidity. Since talc is relativelythicker than mica, it is preferably smaller in size so that it isdispersed in the resin as finely as mica. The average particle diameterof talc is measured by a microtrack laser diffraction method.

Talc is not limited by the place of production and so on. It preferablyhas a high SiO₂ content, for example, 60 wt % or more. When talc has ahigh. SiO₂ content, the content of Fe₂O₃ which is an impurity is apt tobecome relatively low. Therefore, talc is advantageous in terms ofcolor. A method of grinding a talc ore is not particularly limited andmay be an axial-flow milling method, annular milling method, rollmilling method, ball milling method, jet milling method, vessel rotarycompression shear milling method or the like. Talc is preferablyagglomerated from the viewpoint of handling properties. To produceagglomerated talc, such methods are available as one making use ofdeaeration and compression, one in which a binder resin is used forcompression. The method making use of deaeration and compression ispreferred because it is simple and prevents an unrequired binder resincomponent from being contained in the composition of the presentinvention.

Wollastonite as the component “d” is a natural white mineral havingneedle-like crystals mainly composed of calcium silicate andsubstantially represented by a chemical formula CaSiO₃. It generallycontains SiO₂ in an amount of about 50 wt %, CaO in an amount of about47 wt % and others including Fe₂O₃ and Al₂O₃ and has a specific gravityof about 2.9.

Preferably, wollastonite has such a particle size distribution thatparticles having a size of 3 μm or more account for 75% or more andparticles having a size of 10 μm or more account for 5% or less and anaspect ratio L/D (length/diameter) of 3 or more, particularly preferably8 or more. When particles having a size of 3 μm or more account for 75%or more and particles having a size of 10 μm or more account for 5% orless in the particle size distribution, the wollastonite has asatisfactory reinforcing effect to improve flame retardancy easily andis finely dispersed in the resin to obtain excellent resistance to wetheat. When the aspect ratio is 8 or more, a satisfactory reinforcingeffect is obtained. When work environment is taken into consideration,wollastonite having an aspect ratio of 50 or less, preferably 40 or lessare advantageous. Wollastonite may be surface treated with an ordinarysurface treatment agent, for example, a coupling agent such as asilane-based coupling agent or titanate-based coupling agent.

The resin composition-I of the present invention comprises fourcomponents “a”, “b”, “c” and “d” as essential ingredients. The amountsof these essential ingredients of the resin composition-I will bedescribed below. The amounts of the components “a”, “b” and “c” in theresin composition are expressed based on the total weight of the threecomponents. The component “a” is; contained in an amount of 40 to 92 wt%, the component “b” in an amount of 5 to 40 wt % and the component “c”in an amount of 3 to 20 wt % based on 100 wt % of the total of the threecomponents. When the component “a” is contained in an amount of lessthan 40 wt % or the component “b” is contained in an amount of more than40 wt %, heat resistance (especially deflection temperature under load)and mechanical strength lower. When the component “a” is contained in anamount of more than 92 wt % or the component “b” is contained in anamount of less than 5 wt %, flowability and moldability lower. Further,when the component “c” is contained in an amount of less than 3 wt %,sufficient flame retardancy cannot be obtained and when the component“c” is contained in an amount of more than 20 wt %, mechanical strengthand heat resistance (especially deflection temperature under load)markedly lower and resistance to wet heat greatly lowers.

Preferably, the component “a” is contained in an amount of 50 to 88 wt%, the component “b” in an amount of 7 to 35 wt % and the component “c”in an amount of 5 to 15 wt %.

The amount of the component “d” in the present invention is 0.1 to 30parts by weight, preferably 0.5 to 20 parts by weight based on 100 partsby weight of the total of the components “a”, “b” and “c”. When theamount of the component “d” is smaller than 0.1 part by weight, thecomponent “d” has no effect of improving resistance to wet heat and whenthe amount is larger than 30 parts by weight, its effect of improvingresistance to wet heat is saturated, impact strength lowers and thesurface appearance of the obtained molded product worsens.

The resin composition-I of the present invention may containpolytetrafluoroethylene (component “e”) having fibril formability tofurther improve flame retardancy. The polytetrafluoroethylene havingfibril formability is classified into type 3 according to ASTMstandards. The polytetrafluoroethylene having fibril formability has theproperty of preventing the melt dripping of a test piece at the time ofan UL standard vertical flammability test and are available on themarket under the trade name of Teflon 6J from Dupont-MitsuiFlorochemicals Co., Ltd. or Polyfureon from Daikin Industries Ltd. Theamount of the polytetrafluoroethylene having fibril formability ispreferably 0.1 to 2 parts by weight based on 100 parts by weight of thetotal of the three components “a”, “b” and “c”. When the amount of thepolytetrafluoroethylene is smaller than 0.1 part by weight, satisfactorymelt dripping preventing capability is hardly obtained and when theamount is larger than 2 parts, the appearance of the obtained moldedproduct worsens. The amount of the component “e” is particularlypreferably 0.1 to 1 part by weight.

The polytetrafluoroethylene may be used in the form of an aqueousemulsion or dispersion in addition to a general solid form. Since adispersant component easily exerts a bad influence upon resistance towet heat, the polytetrafluoroethylene in a solid form is preferred.

An agglomerated mixture of an emulsion of the polytetrafluoroethylenehaving fibril formability and an emulsion of a vinyl-based polymer isalso preferred to improve dispersibility in the resin and to obtain anexcellent appearance and mechanical properties.

Examples of the vinyl-based polymer include polypropylene, polyethylene,polystyrene, HIPS, AS resin, ABS resin, MBS resin, MABS resin, AASresin, polymethyl (meth)acrylate, styrene-butadiene block copolymer andhydrogenated copolymer thereof, styrene-isoprene block copolymer andhydrogenated copolymer thereof, acrylonitrile-butadiene copolymer,ethylene-propylene random copolymer and block copolymer, ethylene-butenerandom copolymer and block copolymer, ethylene-α-olefin copolymer,ethylene-unsaturated carboxylic ester copolymer such as ethylene-butylacrylate, acrylic ester-butadiene copolymer such as butylacrylate-butadiene, rubber-like polymer such as polyalkyl(meth)acrylate, composite rubber containing polyorganosiloxane andpolyalkyl (meth)acrylate, copolymer obtained by graft copolymerizing thecomposite rubber with a vinyl-based monomer such as styrene,acrylonitrile or polyalkyl methacrylate, and the like.

Out of these, polystyrene, HIPS, ABS resin, AAS resin, polymethylmethacrylate, composite rubber containing polyorganosiloxane andpolyalkyl (meth)acrylate, and copolymer obtained by graft copolymerizingthe composite rubber with a vinyl-based monomer such as styrene,acrylonitrile or polyalkyl methacrylate are preferred, and a polymer ofthe same kind as the component “b” is more preferred.

To prepare the agglomerated mixture, an aqueous emulsion of thecomponent “b” having an average particle diameter of 0.01 to 1 μm,particularly 0.05 to 0.5 μm is mixed with an aqueous emulsion ofpolytetrafluoroethylene having an average particle diameter of 0.05 to10 μm, particularly 0.05 to 1.0 μm. The emulsion ofpolytetrafluoroethylene is obtained by emulsion polymerizingpolytetrafluoroethylene using a fluorine-containing surfactant. In theemulsion polymerization, other comonomer such as hexafluoropropylene maybe copolymerized in an amount of 10 wt % or less based on thepolytetrafluoroethylene.

To obtain the agglomerated mixture, an appropriatepolytetrafluoroethylene emulsion preferably has a solid contents of 40to 70 wt %, particularly preferably 50 to 65 wt % and a styrene-basedresin emulsion as the component “b” preferably has a solid contents of25 to 60 wt %, particularly preferably 30 to 45 wt %. Further, theamount of the polytetrafluoroethylene in the agglomerated mixture ispreferably 5 to 40 wt %, particularly preferably 10 to 30 wt % based on100 wt % of the total of it and the vinyl-based polymer used in theagglomerated mixture. A preferred production method is to mix and stirthe above emulsion and charge it into hot water containing a metal saltsuch as calcium chloride or magnesium sulfate to salt out and solidifythe emulsion for separation and recovery. An alternative method is torecover a stirred mixed emulsion by spray drying or freeze drying.

An agglomerated mixture of an emulsion of polytetrafluoroethylene havingfibril formability and an emulsion of a vinyl-based polymer in variousforms can be used. For example, the agglomerated mixture may be in sucha form that each polytetrafluoroethylene particle is covered with thevinyl-based polymer, such a form that the vinyl-based polymer is coveredwith polytetrafluoroethylene, or such a form that several particlescohere to one particle.

Further, a mixture obtained by graft polymerizing the same or differentvinyl-based monomer to the outer layer of an agglomerated mixture mayalso be used. Preferred examples of the vinyl-based monomer includestyrene, α-methylstyrene, methyl methacrylate, cyclohexyl acrylate,dodecyl methacrylate, dodecyl acrylate, acrylonitrile and 2-ethylhexylacrylate. They may be polymerized alone or copolymerized.

The Metabrene A3000 of Mitsubishi Rayon Co., Ltd. is a typical exampleof commercially available product of the agglomerated mixture of anemulsion of polytetrafluoroethylene having fibril formability and anemulsion of a vinyl-based polymer and the preferred component “e” of thepresent invention.

The resin composition-I of the present invention may contain arubber-like polymer (component “f”) to improve its low-temperatureimpact resistance. The rubber-like polymer is a (meth)acrylate-basedcore-shell graft copolymer, polyurethane-based elastomer orpolyester-based elastomer.

When the rubber-like polymer (component “f”) is to be further blendedinto the resin composition-I, it is preferably blended in an amount of 1to 10 parts by weight, particularly preferably 2 to 8 parts by weightbased on 100 parts by weight of the total of the components “a”, “b” and“c”.

As described above, typical examples of the rubber-like polymer as thecomponent “f” are a (meth)acrylate-based core-shell graft copolymer(component “f-1”), polyurethane-based elastomer (component “f-2”) andpolyester-based elastomer (component “f-3”).

The (meth)acrylate-based core-shell graft copolymer (component “f-1”) isa core-shell polymer consisting of a core which is of a rubber-likealkyl (meth)acrylate polymer having an alkyl group with 2 to 8 carbonatoms, of a copolymer with a diene-besed rubber like polymer and of amixture of the above two polymers, and a shell formed by polymerizing analkyl (meth)acrylate and optionally a copolymerizable vinyl monomer, ora multi-layer core-shell polymer formed likewise. A core-shell polymercomprising a core of a diene-based rubber-like polymer alone may also beused. Commercial products of the (meth)acrylate core-shell graft polymerinclude the HIA-15 and HIA-28 of Kureha Chemical Industry Co., Ltd.Commercial products of the core-shell polymer comprising a core of adiene-based rubber-like polymer alone include the Paraloid EXL-2602 ofKureha Chemical Industry Co., Ltd.

Further, a polymer (to be referred to as “IPN type polymer” hereinafter)obtained by graft polymerizing a composite rubber having such astructure that a polyorganosiloxane component and a poly(meth)alkylacrylate component are entangled with each other so that they cannot beseparated from each other with an alkyl (meth)acrylate and optionally acopolymerizable vinyl monomer may also be used as the component “f-1”.Commercial products of the IPN type polymer include the Metablen S-2001of Mitsubishi Rayon Co., Ltd. The component “f-1” will be described indetail hereinafter.

The polyurethane-based elastomer (component “f-2”) as another example ofthe rubber-like polymer (component “f”) is obtained from a reactionamong an organic polyisocyanate, polyol and chain extending agent havingtwo or three functional groups and a molecular weight of 50 to 400, andknown thermoplastic polyurethane elastomers may be used. The Kuramiron Uof Kuraray Co., Ltd. is easily acquired as the thermoplasticpolyurethane elastomer.

The polyester-based elastomer (component “f-3”) as still another exampleof the rubber-like polymer (component “f”) is obtained by polycondensinga dicarboxylic acid component, alkylene glycol component andpolyalkylene glycol component, and known thermoplastic polyesterelastomers may be used. The Pelprene of Toyobo Co., Ltd., the Nouvelanof Teijin Limited and the like are easily acquired as the thermoplasticpolyester elastomer.

When the present inventors have conducted studies on the improvement ofthe physical properties of the above resin composition-I, it has beenfound that a composition obtained by further blendingpolytetrafluoroethylene having fibril formability (component “e”) and a(meth)acrylate-based core-shell graft copolymer (component “f-1”) inspecific amounts with the resin composition-I which comprises thecomponents “a”, “b”, “c” and “d” as essential ingredients has moreexcellent characteristic properties.

According to the present invention, there is provided the followingresin composition-II which comprises:

(A) 40 to 92 wt % of an aromatic polycarbonate resin (component “a”),

(B) 5 to 40 wt % of a styrene-based resin (component “b”),

(C) 3 to 20 wt % of a phosphate-based flame retardant (component “c”),

(D) 0.1 to 30 parts by weight of a silicate filler (component “d”) basedon 100 parts by weight of the total of the components “a”, “b” and “c”,

(E) 0.1 to 2 parts by weight of polytetrafluoroethylene having fibrilformability (component “e”) based on 100 parts by weight of the total ofthe components “a”, “b” and “c”, and

(F) 1 to 10 parts by weight of a (meth)acrylate-based core-shell graftcopolymer (component “f-1”) based on 100 parts by weight of the total ofthe components “a”, “b” and “c”, and

which has a chlorine compound in terms of chlorine atoms of 100 ppm orless.

The resin composition-II of the present invention is characterized inthat it further comprises the components “e” and “f” as essentialingredients unlike the above resin composition-I. In the resincomposition-II, the components “a”, “b”, “c” and “d” are substantiallyidentical to those of the resin composition-I and used in the sameamounts as in the resin composition-I. The same compound as thatdescribed as an optional component of the resin composition-I is used inthe same amount as the component “e”.

In the resin composition-II, the (meth)acrylate-based core-shell graftcopolymer (component “f-1”) which is one kind of rubber-like polymer(component “f”) is used as an essential ingredient. This component “f-1”is used in an amount of 0.1 to 10 parts by weight, preferably 2 to 8parts by weight based on 100 parts by weight of the total of thecomponents “a”, “b” and “c”.

A detailed description is given of the component “f-1”.

The (meth)acrylate-based core-shell graft copolymer (component “f-1”) isa copolymer containing an acrylate or methacrylate as the essentialingredient of a core or shell.

The core of the (meth)acrylate-based core-shell graft copolymer is madefrom a homopolymer of one monomer, a copolymer of two or more monomers,or a copolymer having a so-called IPN (Inter-Penetrating-Network)structure that two or more homopolymers and copolymers are entangledwith each other. The (meth)acrylate-based core-shell graft copolymercomprising any one of the cores may be used.

The proportion of the core to,the (meth)acrylate-based core-shell graftcopolymer, that is, the proportion of the rubber component must be 30 wt% or more. It is preferably 40 wt % or more, particularly preferably 50wt % or more. The upper limit is 95 wt %, preferably 90 wt %,particularly preferably 85 wt %. A portion other than the core forms ashell.

The average particle diameter of the core is preferably in the range of0.08 to 0.6 μm. When the average particle diameter is smaller than 0.08μm, the improvement of impact resistance becomes unsatisfactory and whenthe average particle diameter is larger than 0.6 μm, the appearance of amolded product is worsened.

The shell of the (meth)acrylate-based core-shell graft copolymer may beformed by graft polymerizing a homopolymer of one monomer, graftcopolymerizing two or more monomers at the same time, or graftpolymerizing one or more monomers in multiple stages. The(meth)acrylate-based core-shell graft copolymer comprising any one ofthe shells may be used.

The above cores and shells may be combined in the (meth)acrylate-basedcore-shell graft copolymer as the component “f-1”.

The core may be made from acrylic rubber, butadiene rubber, isoprenerubber, styrene-butadiene rubber, butyl rubber, ethylene-propylene-dienerubber, chloroprene rubber, nitrile rubber, silicon rubber orepichlorohydrin rubber. Out of these rubber components, butadienerubber, isoprene rubber, styrene-butadiene rubber and acrylic rubber arepreferred from the viewpoint of impact resistance and butadiene rubberis particularly preferred.

And also a copolymer rubber with at least one monomer selected from anacrylic ester, methacrylic ester, butadiene, isoprene, isobutylene,ethylene, propylene, α-olefin, ethylidene norbornene, dicyclopentadieneand styrene may be used as the core. This copolymer rubber is preferablyused because it can well balance impact resistance, flame retardancy,resistance to wet heat and the like. Out of the above copolymer rubbercomponents, copolymer rubbers of an acrylic ester and/or methacrylicester and at least one monomer selected from butadiene, isoprene,isobutylene, ethylene, propylene, α-olefin, ethylidene norbornene,dicyclopentadiene and styrene are preferred. Copolymers of an acrylicester and/or methacrylic ester and butadiene and/or isoprene are morepreferred and copolymers of an acrylic ester and/or methacrylic esterand butadiene are particularly preferred.

IPN rubbers having such a structure that a silicon rubber component anda rubber component selected from an acrylic rubber component, butadienerubber component, isoprene rubber component, isobutylene rubbercomponent, ethylene-propylene-diene rubber component and copolymerizingcomponent thereof are entangled with each other so that they cannot beseparated from each other may be used. The IPN rubbers have excellentflame retardancy because they contain a silicon rubber component andexcellent impact resistance due to their entangled structure between thesilicon rubber component and other rubber component. Out of these IPNrubbers, IPN rubbers comprising a silicon rubber component and acrylicrubber component and/or isobutylene rubber component are preferred andIPN rubbers having such a structure that a silicon rubber component andan acrylic rubber component are entangled with each other so that theycannot be separated from each other are more preferred.

As the monomer component forming the shell may be used at least onemember selected from acrylic esters, methacrylic esters, aromatic vinylcompounds and vinyl cyanide compounds and other monomer copolymerizablewith these. Examples of the copolymerizable other monomer include maleicanhydride, maleimide, N-methylmaleimide, N-phenylmaleimide,N-cyclohexylmaleimide and the like.

Preferably, the acrylic ester or methacrylic ester used in the acrylicrubber, copolymer rubber or IPN rubber of the core of the(meth)acrylate-based core-shell graft copolymer as the component “f-1”has an alkyl group having 2 to 12 carbon atoms. Examples of the acrylicester include methyl acrylate, ethyl acrylate, n-propyl acrylate,n-butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate and thelike. Out of these, n-butyl acrylate and 2-ethylhexyl acrylate arepreferred. Examples of the methacrylic ester include hexyl methacrylate,2-ethylhexyl methacrylate, n-lauryl methacrylate and the like.

An organosiloxane used in the silicon rubber or IPN rubber of the coreof the (meth)acrylate-based core-shell graft copolymer as the component“f-1” has a 3 or more-membered ring, preferably 3- to 6-membered ring.Examples of the organosiloxane include hexamethylcyclotrisiloxane,octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane,tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxaneand the like. They may be used alone or in admixture of two or more.

Preferably, the acrylic ester:or methacrylic ester used in the shell ofthe (meth)acrylate-based core-shell graft copolymer as the component“f-1” has an alkyl group having 1 to 8 carbon atoms. Examples of theacrylic ester include methyl acrylate, ethyl acrylate, n-butyl acrylate,hydroxyethyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzylacrylate and the like. Examples of the methacrylic ester include methylmethacrylate, ethyl methacrylate, propyl methacrylate, 2-ethylhexylmethacrylate, butyl methacrylate, hydroxyethyl methacrylate, glycidylmethacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzylmethacrylate and the like. Out of these, methyl methacrylate ispreferred.

Examples of the aromatic vinyl compound used in the shell of the(meth)acrylate-based core-shell graft copolymer as the component “f-1”include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene andthe like. Out of these, styrene is preferred. Examples of the vinylcyanide compound include acrylonitrile and methacrylonitrile. Out ofthese, acrylonitrile is preferred.

A crosslinkable monomer or graft crossing agent may be contained in thecore or shell of the (meth)acrylate-based core-shell graft copolymer asthe component “f-1”. Particularly when a conjugated diene-basedcomponent is not contained, they are preferably used.

Examples of the monomer crosslinkable with acrylic esters andmethacrylic esters include aromatic divinyl compounds such asdivinylbenzene,.ethylene glycol dimethacrylate, propylene glycoldimethacrylate, 1,3-butylene glycol dimethacrylate, 1,4-butylene glycoldimethacrylate, allyl methacrylate and the like. Out of these, allylmethacrylate and ethylene glycol dimethacrylate are preferred.

Examples of the graft crossing agent for acrylic esters and methacrylicesters include allyl methacrylate, triallyl cyanurate, triallylisocyanurate and the like.

Examples of the monomer crosslinkable with organosiloxanes includesilane-based compounds having a functionality of 3 or 4 such astrimethoxymethylsilane, triethoxyphenylsilane, tetramethoxysilane,tetraethoxysilane, tetra-n-propoxysilane, tetrabutoxysilane and thelike. Out of these, crosslinkable monomers having a functionality of 4are preferred and tetraethoxysilane is particularly preferred.

Examples of the graft crossing agent for organosiloxanes includecompounds which can form units represented by the following formulas(2), (3) and (4).

 CH₂═CH—SiR¹ _(n)O_((3-n)/2)  (3)

HSCH₂_(p)SiR¹ _(n)O_((3-n)/2)  (4)

wherein R¹ is a methyl group, ethyl group, propyl group or phenyl group,R² is a hydrogen atom or methyl group, n is 0, 1 or 2, and p is aninteger of 1 to 6.

Since an acryloyloxysiloxane or methacryloyloxysiloxane capable offorming the unit of the formula (2) has high graft efficiency, it canform an effective graft chain, which is advantageous in developingimpact resistance. A methacryloyloxysiloxane capable of forming the unitof the formula (2) is particularly preferred. Examples of themethacryloyloxysiloxane include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropyl methoxydimethylsilane,γ-methacryloyloxypropyl dimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyl ethoxydiethylsilane,γ-methacryloyloxypropyl diethoxymethylsilane and δ-methacryloyloxybutyldiethoxymethylsilane.

Out of the above (meth)acrylate-based core-shell graft copolymers as thecomponent “f-1”, the following graft copolymers are more preferred.

Preferred Graft Copolymers

(Meth)acrylate-based core-shell graft copolymers, each consisting of 40to 90 wt % of a core made from a rubber selected from (i) a rubberconsisting of 60 to 100 wt % of butadiene and 0 to 40 wt % of styrene,(ii) a copolymer rubber consisting of 60 to 90 wt % of an acrylic esterand 10 to 40 wt % of butadiene and (iii) a composite rubber consistingof 5 to 95 wt % of an organosiloxane polymer component and 5 to 95 wt %of a polymer component consisting of an acrylic ester and/or methacrylicester and having such a structure that the organosilane polymercomponent and the polymer component are entangled with each other sothat they cannot be separated from each other and 10 to 60 wt % of ashell made from a polymer or copolymer comprising one or more monomersselected from an acrylic ester, methacrylic ester, aromatic vinylcompound and vinyl cyanide compound.

Out of the above “preferred graft copolymers”, the following graftcopolymers (1) to (3) are particularly preferred.

Graft Copolymer (1)

A graft copolymer (may be referred to as “graft copolymer (1)”hereinafter) consisting of 40 to 90 wt % of a core made from a rubberconsisting of 60 to 100 wt % of butadiene and 0 to 40 wt % of styrene asa core and 10 to 60 wt % of a shell formed by graft polymerizing amethacrylic ester as an essential ingredient and one or more monomersselected from an aromatic vinyl compound, acrylic ester and vinylcyanide compound as required by bulk polymerization, suspensionpolymerization, bulk-suspension polymerization, solution polymerizationor emulsion polymerization, particularly emulsion polymerization.

The proportion of the core to the graft copolymer (1) is preferably 60to 85 wt %, more preferably 65 to 80 wt %. When the proportion of thecore is 60 to 85 wt %, it is possible to improve impact resistance andachieve excellent flame retardancy at the same time. A butadiene rubberis more preferred as the core.

A polymer or copolymer consisting of 30 to 100 wt % of a methacrylicester and 0 to 70 wt % of an aromatic vinyl compound and/or an acrylicester based on 100 wt % of the total is preferred as the shell. Methylmethacrylate is preferred as the methacrylic ester. A polymer orcopolymer consisting of 60 to 100 wt % of methyl methacrylate and 10 to40 wt % of an acrylic ester such as ethyl acrylate is particularlypreferred.

Therefore, the graft copolymer (1) is particularly preferably a graftcopolymer consisting of 65 to 80 wt % of a butadiene rubber as the corebased on 100 wt % of the total weight of the copolymer and 20 to 35 wt %of a polymer or copolymer consisting of 60 to 100 wt % of methylmethacrylate and 0 to 40 wt % of an acrylic ester such as ethyl acrylatebased on 100 wt % of the total weight of the shell.

The graft copolymer (1) is advantageous in improving impact resistancebecause its core is mainly made from a butadiene rubber component whichis very effective in improving impact resistance. Therefore, it ispreferably used when a condensed phosphoric ester whose impactresistance readily lowers slightly is used, that is, n is not “0” as theaverage value in the above formula (1), preferably 0.5 to 3.

Graft Copolymer (2)

A copolymer (may be referred to as “graft copolymer (2)” hereinafter)consisting of 40 to 90 wt % of a core made from a copolymer rubberconsisting of 60 to 90 wt % of an acrylic ester and 10 to 40 wt % ofbutadiene and 10 to 60 wt % of a shell formed by graft polymerizing atleast one selected from an acrylic ester, methacrylic ester, aromaticvinyl compound and vinyl cyanide compound in one stage or multiplestages based on 100 wt % of the total of the core and the shell.

The copolymer preferably consists of 50 to 75 wt % of the core and 25 to50 wt % of the shell, more preferably 50 to 70 wt % of the core and 30to 50 wt % of the shell.

As for the ratio of the acrylic ester to butadiene in the core, it ismore preferred that the amount of the acrylic ester should be 60 to 80wt % and the amount of butadiene should be 20 to 40 wt % based on 100 wt% of the total weight of the core. The core may contain othercopolymerizable monomer, preferably a methacrylic ester or aromaticvinyl in an amount of 20 wt % or less based on 100 wt % of the totalweight of the core.

Since the graft copolymer (2) contains an acrylic ester component havingexcellent weatherability and flame retardancy and a butadiene componenthaving excellent impact resistance in the core in a well balancedmanner, it is possible to obtain a resin composition which is wellbalanced among characteristic properties such as flame retardancy,impact resistance, weatherability and coloring.

The acrylic ester used in the core of the graft copolymer (2) ispreferably n-butyl acrylate or 2-ethylhexyl acrylate, particularlypreferably 2-ethylhexyl acrylate. The methacrylic ester used in theshell is particularly preferably methyl methacrylate.

The average particle diameter of the core of the graft copolymer (2) ispreferably 0.08 to 0.25 μm, particularly preferably 0.13 to 0.20 μm.

The shell of the graft copolymer (2) is made from a polymer or copolymercomprising at least one selected from an aromatic vinyl compound, vinylcyanide compound, methacrylic ester and acrylic ester. The polymer orcopolymer preferably contains an aromatic vinyl compound and amethacrylic ester, particularly preferably a methacrylic ester, so as tomake use of the excellent characteristic properties of the core.

As for the ratio of the monomers of the shell of the graft copolymer(2), the amount of the methacrylic ester is preferably 45 to 80 wt %,more preferably 55 to 70 wt % based on 100 wt % of the total weight ofthe shell. Therefore, the total amount of the aromatic vinyl compoundand other component is preferably 20 to 55 wt %, more preferably 30 to45 wt %. When the shell further contains a vinyl cyanide compound and anacrylic ester, the total amount of these is preferably 20 to 35 wt %,more preferably 22 to 30 wt % based on 100 wt % of the total includingthe aromatic vinyl compound. The other component is preferably a vinylcyanide compound.

The shell of the graft copolymer (2) of the present invention ispreferably formed by two-stage graft polymerization, the graft componentof the first stage is a mixture of an aromatic vinyl compound and amethacrylic ester or a mixture of an aromatic vinyl compound, vinylcyanide compound and a methacrylic ester, the graft component of thesecond stage is a methacrylic ester, and the shell consists of thefirst-stage graft component in an amount of 40 to 75 wt % and thesecond-stage graft component in an amount of 25 to 60 wt %, morepreferably the first-stage graft component in an amount of 42 to 70 wt %and the second-stage graft component in an amount of 30 to 58 wt %.

Further, the graft copolymer (2) of the present invention may contain acrosslinkable monomer and a graft crossing agent as required when thecore of the copolymer and the shell of each stage are polymerized. Thetotal amount of these components is 0.01 to 3 wt % based on 100 wt % ofthe total weight of the monomers used for the polymerization of the coreor 0.01 to 2 wt % based on 100 wt % of the total weight of the monomersof each stage for the polymerization of the shell of each stage.

The graft copolymer (2) may be subjected to an anti-blocking improvingtreatment to eliminate a dispersion failure at the time of theproduction of the resin composition of the present invention. Knownmethods for improving antiblocking properties may be employed.

The methods include one in which a latex of the graft copolymer issprayed and dried to obtain spherical powders, one in which conditionsfor salting out a latex of the copolymer are adjusted, and one in whichan additive such as a lubricant is added. There is also available one inwhich 0.1 to 25 parts by weight of a graft copolymer which has improvedcharacteristic properties of powder and is obtained by graftpolymerizing 5 to 49 wt % of an elastic trunk polymer with 51 to 95 wt %of a monomer forming a hard polymer is blended into 100 parts by weightof the graft copolymer (2) in the form of a slurry. The expression“elastic trunk polymer” as used herein denotes a polymer or copolymer ofmonomers used in the core of the graft copolymer (2) and the expression“monomer forming a hard polymer” denotes a monomer used in the shell ofthe graft copolymer (2).

Alternatively, one in which an emulsion of a hard non-elastic polymer isadded to a slurry of the solidified graft copolymer (2) may be used. Thehard non-elastic polymer is a polymer of at least one monomer selectedfrom an aromatic vinyl compound, vinyl cyanide compound and methacrylicester. It preferably contains methyl methacrylate in an amount of 80 wt% or more.

Out of the above methods for the improvement of anti-blockingproperties, one in which a graft copolymer having improvedcharacteristic properties of powder or hard non-elastic polymer isblended into the graft copolymer (2) in the form of a slurry ispreferred because anti-blocking properties can be achieved simply andeffectively. The method for improving anti-blocking properties by addingthe graft copolymer having improved characteristic properties of powderor hard non-elastic polymer is carried out with the above range of eachcomponent of the graft copolymer (2) of the present invention.

The particularly preferred graft copolymer (2) consists of 50 to 70 wt %of a core made from a rubber latex which consists of 60 to 80 wt % of anacrylic ester and 20 to 40 wt % of butadiene and 30 to 50 wt % of ashell obtained by graft polymerizing a mixture of an aromatic vinylcompound and a methacrylic ester and a vinyl cyanide compound asrequired in two stages based on 100 wt % of the total of the core andthe shell. The methacrylic ester is contained in the shell in an amountof 55 to 70 wt % based on 100 wt % of the shell. When the vinyl cyanidecompound is contained, it is used in an amount of 22 to 30 wt % based on100 wt % of the total of the vinyl cyanide compound and the aromaticvinyl compound. The first graft component is a mixture of an aromaticvinyl compound and a methacrylic ester or a mixture of an aromatic vinylcompound, vinyl cyanide compound and methacrylic ester, the second graftcomponent is a methacrylic ester, the first graft component is used inan amount of 42 to 70 wt %, and the second graft component is used in anamount of 30 to 58 wt % based on 100 wt % of the total of the shellcomponents. Illustrative examples of the graft copolymer (2) include theHIA-15, HIA-28 and HIA-28S of Kureha Chemical Industry, Co., Ltd.

Graft Copolymer (3)

A graft copolymer (may be referred to as “graft copolymer (3)”hereinafter) consisting of 40 to 90 wt % of a core made from a compositerubber which consists of 5 to 95 wt % of an organosiloxane polymercomponent and 5 to 95 wt % of a polymer component consisting of anacrylic ester and/or methacrylic ester and having such a structure thatthese components are entangled with each other so that they cannot beseparated from each other and 10 to 60 wt % of a shell made from apolymer or copolymer of one or more monomers selected from an acrylicester, methacrylic ester, aromatic vinyl compound and vinyl cyanidecompound.

As for the ratio of the organosiloxane polymer component to the polymercomponent consisting of an acrylic ester and/or methacrylic ester in thecore, the amount of the organosiloxane polymer component is preferably 5to 70 wt %, more preferably 6 to 60 wt %, the most preferably 7 to 50 wt%, and the amount of the acrylic ester and/or methacrylic ester ispreferably 30 to 95 wt %, more preferably 40 to 94 wt %, the mostpreferably 50 to 93. wt % based on 100 wt % of the total weight of thesecomponents.

The amount of the composite rubber as the core in the graft copolymer(3) is preferably 60 to 90 wt %, more preferably 60 to 85 wt % based on100 wt % of the total weight of the copolymer. When the amount is 60 to90 wt %, it is possible to improve impact resistance and achieveexcellent flame retardancy at the same time.

The average particle diameter of the composite rubber is preferably 0.08to 0.6 μm, more preferably 0.1 to 0.4 μm.

To produce the composite rubber of the graft copolymer (3), emulsionpolymerization is the most appropriate. It is preferred that anorganosiloxane polymer latex should be first prepared and an acrylicester monomer and/or methacrylic ester monomer should be impregnatedinto the rubber particles of the organosiloxane polymer latex and thenpolymerized.

The organosiloxane polymer component forming the composite rubber can beprepared by emulsion polymerizing an organosiloxane shown below in thepresence of the above monomer crosslinkable with organosiloxane, and theabove graft crossing agent for organosiloxane may be used in theemulsion polymerization.

The organosiloxane has a 3 or more-membered ring, preferably 3- to6-membered ring, as exemplified by hexamethylcyclotrisiloxane,octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane,dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane,tetramethyltetraphenylcyclotetrasiloxane, octaphenylcyclotetrasiloxaneand the like. They may be used alone or in admixture of two or more. Theamount of the organosiloxane is 50 wt % or more, preferably 70 wt % ofmore based on the polyorganosiloxane rubber component.

The crosslinkable monomer is preferably tetrafunctional, particularlypreferably tetraethoxysilane. The amount of the crosslinkable monomer inthe organosiloxane polymer component in the composite rubber of thegraft copolymer (3) is 0.1 to 30 wt %, preferably 0.5 to 10 wt % basedon 100 wt % of the organosiloxane polymer component. What have beenenumerated above may be used as the graft crossing agent and its amountis 0 to 10 wt % based on the organosiloxane polymer component.

The organosiloxane polymer latex can be produced by methods disclosed byU.S. Pat. No. 2891920 and U.S. Pat. No. 3294725, for example. Forinstance, the latex is preferably produced by a method which comprisesmixing a mixed solution of an organosiloxane and a crosslinkable monomerand optionally a graft crossing agent with water by shearing using ahomogenizer in the presence of an sulfonic acid-based emulsifier such asan alkylbenzenesulfonic acid or alkylsulfonic acid. Thealkylbenzenesulfonic acid is preferred because it serves as anemulsifier for the organosiloxane and also a polymerization initiator.When an alkylbenzenesulfonic acid metal salt or alkylsulfonic acid metalsalt is used at this point, it is effective in maintaining the polymerstably during graft polymerization.

The polymer consisting of an acrylic ester and/or methacrylic ester andforming the composite rubber is produced by adding the above acrylicester and/or methacrylic ester, crosslinkable monomer and graft crossingagent to the organosiloxane polymer latex which has been neutralized byadding an aqueous solution of alkali such as sodium hydroxide, potassiumhydroxide or sodium carbonate to impregnate them into the organosiloxanepolymer rubber particles and causing an ordinary radical polymerizationinitiator to function. The total amount of the crosslinkable monomer andgraft crossing agent for the acrylic ester and so on is 0.1 to 20 wt %,preferably 0.5 to 10 wt % based on 100 wt % of the polymer consisting ofan acrylic ester and/or methacrylic ester.

Along with the proceeding of polymerization, the crosslinking network ofthe polymer consisting of an acrylic ester and/or methacrylic esterwhich is entangled with the crosslinking network of the organosiloxanepolymer rubber is formed and a latex of the composite rubber consistingof the organosiloxane polymer and the polymer consisting of an acrylicester and/or methacrylic ester which cannot be substantially separatedfrom each other is thereby obtained.

The composite rubber preferably has such a structure that the mainskeleton of the organosiloxane polymer has a dimethysiloxane recurringunit and the main skeleton of the polymer consisting of an acrylic esterand/or methacrylic ester has an n-butyl acrylate recurring unit.

The composite rubber prepared by emulsion polymerization can be graftcopolymerized with a vinyl-based monomer and the organosiloxane polymercomponent and the polymer component consisting of an acrylic esterand/or methacrylic ester are firmly entangled with each other so thatthey cannot be extracted and separated from each other with an ordinaryorganic solvent such as acetone or toluene. The gel content of thiscomposite rubber measured by extracting with toluene at 90° C. for 12hours is 80 wt % or more.

Examples of the vinyl-based monomer to be graft polymerized with thecomposite rubber include the above aromatic vinyl compound, methacrylicester, acrylic ester, vinyl cyanide compound and the like. They may beused alone or in combination of two or more.

The graft copolymer (3) can be separated and recovered by charging alatex obtained by adding the above vinyl-based monomer to a compositerubber latex and polymerizing them in a single stage or multiple stagesby a radical polymerization technique into hot water containing a metalsuch as calcium chloride or magnesium sulfate, salting-out andsolidification.

The preferred graft copolymer (3) consists of 60 to 85 wt % of a coremade from a composite rubber having such a structure that 7 to 50 wt %of an organosiloxane polymer component and 50 to 93 wt % of an acrylicester and/or methacrylic ester are entangled with each other so thatthey cannot be separated from each other and 15 to 40 wt % of a shellmade from a polymer or copolymer of one or more monomers selected froman acrylic ester, methacrylic ester, aromatic vinyl compound and vinylcyanide compound based on 100 wt % of the total of the core and theshell.

The (meth)acrylic core-shell graft copolymer as the component “f-1” ofthe present invention may be a mixture of the above graft polymer and apolymer or copolymer obtained by polymerizing 70 to 100 wt % of one ormore monomers selected from a methacrylic ester, acrylic ester, aromaticvinyl compound and vinyl cyanide compound with 0 to 30 wt % of othermonomer copolymerizable with the above monomer as forming shellcomponent. The polymer and copolymer components may be mixed separatelyin addition to a free polymer and/or copolymer formed in the course ofgraft polymerization.

Out of the above preferred graft copolymers (1) to (3), the graftcopolymer (2) is superior to the other graft copolymers in both theflame retarding effect and coloring. The flame retarding effect andcoloring of the graft copolymer (2) are marked when the proportion ofthe phosphate-based flame retardant as the component “c” is relativelysmall.

The resin composition can be produced by mixing the above componentswith a mixer such as a tumbler, V-type blender, Nauta mixer, Banburymixer, kneading roll or extruder. Further, other thermoplastic resinsuch as a polyester, polyamide or polyphenylene ether may be mixed inlimits not prejudicial to the object of the present invention and apolyorganosiloxane-based flame retardant can be blended.

Additives which are generally blended in trace amounts, such as a heatstabilizer (such as a phosphoric ester or phosphorous ester),antioxidant (such as a hindered phenol-based compound), a lightstabilizer (such as a benzotriazole-based compound, hindered amine-basedcompound or benzophenone-based compound), colorant, foaming agent andantistatic agent, can be blended. They may be blended alone or in theform of a master pellet of these resins.

The heat stabilizer is a known phosphorous acid, phosphoric acid,phosphonous acid, phosphonic acid or ester thereof. Illustrativeexamples of the heat stabilizer include phosphite compounds such astriphenyl phosphite, trisnonylphenyl phosphite,tris(2,4-di-tert-butylphenyl)phosphite, tridecyl phosphite, trioctylphosphite, trioctadecyl phosphite, didecylmonophenyl phosphite,dioctylmonophenyl phosphite, diisopropylmonophenyl phosphite,monobutyldiphenyl phosphite, monodecyldiphenyl phosphite,monooctyldiphenyl phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite,2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite,bis(nonylphenyl)pentaerythritol diphosphite andbis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite; phosphatecompounds such as tributyl phosphate, trimethyl phosphate, tricresylphosphate, triphenyl phosphate, trichlorophenyl phosphate, triethylphosphate, diphenylcresyl phosphate, diphenylmonoorthoxenyl phosphate,tributoxyethyl phosphate, dibutyl phosphate, dioctyl phosphate anddiisopropyl phosphate; and phosphonite compounds such astetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenylene diphosphonite,tetrakis(2,4-di-tert-butylphenyl)-4,3′-biphenylene diphosphonite,tetrakis (2,4-di-tert-butylphenyl)-3,3′-biphenylene diphosphonite andbis(2,4-di-tert-butylphenyl)-4-biphenylene diphosphonite as otherphosphorus-based heat stabilizers. Out of these, preferred aretrisnonylphenyl phosphite, distearylpentaerythritol diphosphite,bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite,tris(2,4-di-tert-butylphenyl)phosphite, triphenyl phosphate, trimethylphosphate and tetrakis(2,4-di-tert-butylphenyl)-4,4′-biphenylenediphosphonite. These heat stabilizers may be used alone or in admixtureof two or more.

Besides the above heat stabilizers, a hindered phenol-based compound orsulfur-based compound which is generally known as an antioxidant ispreferably blended as the heat stabilizer of the present invention. Thecompound is preferred because it retains the heat stability of astyrene-based resin and suppresses the heat decomposition of the resin.Illustrative examples of the compound includen-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate,4,4′-butylidenebis(3-methyl-6-tert-butylphenol),4,4′-thiobis(3-methyl-6-tert-butylphenol),2,2′-methylenebis(4-methyl-6-tert-butylphenol),tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate,2,6-di-tert-butyl-4-methylphenol,2,4-di-tert-amyl-6-[1-(3,5-di-tert-amyl-2-hydroxyphenyl)ethyl]phenylacrylate, pentaerythrityl tetrakis(3-laurylthiopropionate),dilauryl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate,distearyl-3,3′-thiodipropionate and the like.

The thus obtained resin composition can be easily formed by extrusionmolding, injection molding or compression molding, particularlypreferably injection molding. Blow molding or vacuum molding may also beemployed. The resin composition is the best suited as a material forelectric and electronic parts and OA exterior applications which mustattain UL94V-0 rating.

A molded product of the polycarbonate resin composition of the presentinvention attains V-0 rating in a UL standard 94V flammability testwhile it comprises a phosphate-based flame retardant. In addition, ithas excellent resistance to wet heat and rarely experiences a reductionin impact resistance during its long-term use. Stated more specifically,there can be obtained a molded product which attains V-0 rating as itcomprises a phosphate-based flame retardant and has an impact resistanceretainability of 50% or more when it is stored at a temperature of 65°C. and a relative humidity of 85% for 500 hours and an apparentmolecular weight retainability of 80% or more. It is also possible toobtain a molded product having an impact resistance retainability of 50%or more when it is stored at a temperature of 65° C. and a relativehumidity of 85% for 1,000 hours and an apparent molecular weightretainability of 80% or more. It is the best suited as a material forelectric and electronic parts and OA exterior applications which musthave long service life and resistance to wet heat.

EXAMPLES

The following examples are given to further illustrate the presentinvention. “Parts” in the examples means “parts by weight” andevaluations were made in accordance with the following methods.

(1) resistance to wet heat-1: A ⅛” Izod impact test piece was notchedand subjected to a wet heat treatment with a environmental tester(Platinas Sub-zero Lucifer of Tabai Espec Corp.) at 65° C. and 85% RHfor 500 hours to measure its Izod notched impact resistance value inaccordance with ASTM D256 to be compared with the Izod notched impactresistance value before the wet heat treatment. The retainability isexpressed as the percentage of the value after the wet heat treatment tothe value before the wet heat treatment.

(2) resistance to wet heat-2: The apparent viscosity average molecularweight of a test piece after the wet heat treatment (1) was measured bythe same technique as that for the measurement of the molecular weightof an aromatic polycarbonate resin. That is, the test piece wasdissolved in methylene chloride, an undissolved portion was removed byfiltration to obtain a solution, the specific viscosity of the solutionwas measured in the same manner as the measurement of the viscosityaverage molecular weight of the polycarbonate resin of this text, andthe apparent viscosity average molecular weight was calculated using thesame calculation expression. The retainability is expressed as thepercentage of the value after the wet heat treatment to the value beforethe wet heat treatment.

(3) flame retardancy: A flammability test for a thickness of 1.6 mm wascarried out in accordance with UL standard 94V.

(4) impact resistance: The value of Izod notched impact resistance wasmeasured in accordance with ASTM D256.

I. Description of each Constituent Component

I-(1) Component “a” (Polycarbonate Resin)

Reference Example 1

(Production of Polycarbonate Resin PC-1)

A stirrer shaped like a ribbon was set as an agitation blade in thevessel of a double-axial type of a horizontal axis rotary mixer havingan effective inner volume of 500 liters and equipped with supply port ofan organic solvent for a polycarbonate, hot water supply port, steamintroduction port, vaporized organic solvent exhaust port and overflowtype exhaust port. 50 g of polycarbonate resin granules having anaverage particle diameter of 7 mm and 250 g of water were charged intothe vessel, a methylene chloride solution containing 16 wt % of apolycarbonate resin having an average molecular weight of 22,000 wassupplied at a rate of 10 kg/min under agitation at a rate of 80 rpm whenthe temperature in the vessel reached 77° C., and hot water was alsosupplied at a rate of 10 kg/min. While these were supplied, the volumerate of the amount of the hot water in the vessel to the amount of thepolycarbonate resin granules was maintained at about 5, and thetemperature in the vessel was maintained at 77° C. by heating the steamintroduction port and a jacket using steam having a pressure of 2.7kg/cm². The stirring capacity was 6 kw/hr·m³. After the start of supply,the level of a slurry in the vessel rose, and the formed polycarbonateresin granules and the hot water were exhausted from the exhaust portsequipped in the upper portion of the vessel. At this point, theresidence time of the polycarbonate resin granules was 1 hour.

Thereafter, a sample was collected after the granules were exhausted andthe properties of the granules became stable. The polycarbonate resingranules and hot water exhausted from the exhaust ports were separatedby a vertical centrifugal separator(of Kokusan Enshinki K.K.) at acentrifugal force of 1,500 G and then the polycarbonate resin granuleswere separated by filtration. The separated polycarbonate resin granuleswere;ground to an average particle diameter of 2 mm by a grinder anddried with a hot air drier at 14° C. for 4 hours. The obtainedpolycarbonate resin had a viscosity average molecular weight of 22,000,a bulk density of 0.3 g/cm³ and a chlorine atom content of 5 ppm. Theobtained polycarbonate resin is designated PC-1.

Reference Example 2

(Production of Polycarbonate Resin PC-2)

A polycarbonate resin was produced by the production method shown inReference Example 1 in the same manner as in Reference 1 except that thetemperature in the vessel was set to 70° C. The obtained polycarbonateresin had a viscosity average molecular weight of 22,000, a bulk densityof 0.4 g/cm³ and a chlorine atom content of 50 ppm. The obtainedpolycarbonate resin is designated PC-2.

Reference Example 3

(Production of Polycarbonate resin PC -3)

A polycarbonate resin was produced by the production method shown inReference Example 1 in the same manner as in Reference Example 1 exceptthat the temperature in the vessel was set to 50° C. The thus obtainedpolycarbonate resin had a viscosity average molecular weight of 22,000,a bulk density of 0.65 g/cm³ and a chlorine atom content of 370 ppm. Theobtained polycarbonate resin is designated PC-3.

I-(2) Component “b” (Styrene-based Resin)

Reference Example 4

(Preparation of ABS-1)

After bulk polymerization, a polymer was obtained by a separationcollector comprising a shell and tube heat exchanger and a vacuumchamber and then ABS resin was obtained by pelletizing the polymer witha multi-stage vented double-screw extruder. The ABS resin consisted of15 wt % of acrylonitrile, 20 wt % of butadiene and 65 wt % of styrene.The ABS resin had a weight average molecular weight of a freeacrylonitrile-styrene polymer of 90,000 (in terms of standardpolystyrene measured by GPC), a graft efficiency of 55%, an averagerubber particle diameter obtained by observation through an electronmicroscope of 0.80 μm and a residual acrylonitrile monomer content of250 ppm obtained by measuring a chloroform solution of the ABS resin byliquid chromatography. This ABS resin is designated ABS-1.

Reference Example 5

(Preparation of ABS-2)

ABS-1 obtained in the above Reference Example 4 was charged into astainless steel vessel having an agitating blade, and methanol was addedin an amount (weight ratio) 7 times that of ABS-1 and stirred for 1 hourto wash the ABS-1. Thereafter, the ABS-I was vacuum dried at 60° C. for12 hours. The amount of the residual acrylonitrile monomer in the ABSresin was 80 ppm. This ABS resin is designated ABS-2.

Reference Example 6

(Preparation of ABS-3)

ABS-1 obtained in the above Reference Example 4 was washed with methanolthree times in the same manner as in ABS-2 each for 2 hours and thenvacuum dried at 60° C. for 12 hours. The amount of the residualacrylonitrile monomer in the ABS resin was 20 ppm. This ABS resin isdesignated ABS-3.

Reference Example 7

(Preparation of ABS-4)

10 parts by weight of a polybutadiene latex (solid content), 34.8 partsby weight of styrene and 5.2 parts by weight of acrylonitrile wereemulsion graft polymerized. The obtained graft copolymer was solidifiedwith diluted sulfuric acid, washed, filtered and vacuum dried at 60° C.for 12 hours. The obtained ABS resin comprised 69.5 wt % of styrene, 20wt % of butadiene and 10.5 wt % of acrylonitrile and had a weightaverage molecular weight of a free acrylonitrile-styrene polymer (interms of standard polystyrene measured by GPC) of 120,000, a graftefficiency of 50%, and an average rubber particle diameter measured byobservation through an electron microscope of 0.40 μm and a residualacrylonitrile monomer content measured by liquid chromatography of 50ppm. This ABS resin is designated ABS-4.

I-(3) component “c” (Phosphate-based Flame Retardant)

FR-1: triphenyl phosphate (TPP of Daihachi Chemical Industry Co., Ltd.)

FR-2: resorcinol bis(dixylenyl phosphate) (Adekastab FP-500 of AsahiDenka Kogyo K.K.)

I-(4) component “d” (Silicate Filler)

talc-1: talc (Talc P-3 of Nippon Talc Co., Ltd. having an averageparticle diameter of about 3 μm)

talc-2: talc (HSTO0.8 of Hayashi Kasei Co., Ltd. having an averageparticle diameter of about 5 μm)

WSN-1: wollastonite (WIC10 of KINSEI MATEC Co., Ltd. having an averagefiber diameter of 4.5 μm and an aspect ratio L/D of 8)

WSN-2: wollastonite (Sicatec NN-4 of Tomoe Engineering Co., Ltd. havingan average fiber diameter of 1.5 μm and an aspect ratio L/D of 20)

mica: mica powder (A-41 of YAMAGUCHI MICA Co., Ltd. having an averageparticle diameter of about 40 μm) (filler other than component “d”)

CF: carbon fiber (Besfight HTA-C6-U of Toho Rayon Co., Ltd. based onPAN, having an urethane sizing and diameter of 7 μm)

I-(5) Component “e” (Polytetrafluoroethylene) PTFE:polytetrafluoroethylene (F-201L of Daikin Industries Co., Ltd.)

I-(6) component “f” (Rubber-like Polymer)

rubber-1: methyl methacrylate.2-ethylhexyl acrylate.butadiene.styrenemulti-stage graft copolymer (styrene content of 15 wt %) (HIA-15 ofKureha Chemical Industry Co., Ltd.)

rubber-2: butadiene-based impact modifier (EXL2602 of Kureha ChemicalIndustry Co., Ltd.)

rubber-3: acryl-silicon-based impact modifier (S-2001 of MitsubishiRayon Co., Ltd.)

Examples 1 to 16 and Comparative Examples 1 to 4

Components shown in Table 1 and Table 2 below were mixed together inamounts shown in Table 1 and Table 2 with a V-type blender and theobtained mixtures were pelletized at a cylinder temperature of 240° C.with a vented double-screw extruder having a diameter of 30 mm(TEX30XSST of The Japan Steel Works, Ltd.). The pellets were dried at100° C. for 5 hours and test pieces were formed from the pellets at acylinder temperature of 250° C. and a mold temperature of 70° C. with aninjection molding machine (T-150D of FANUC Ltd.) and evaluated. Theevaluation results are shown in Table 1 and Table 2.

TABLE 1 item unit Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 composition component“a” PC-1 wt % 70 70 70 component “a” PC-2 wt % 70 70 component “a” PC-3wt % component “b” ABS-1 wt % component “b” ABS-2 wt % 20 20 20component “b” ABS-3 wt % 20 component “b” ABS-4 wt % 20 component “c”FR-1 wt % 10 10 10 10 10 component “c” FR-2 wt % * total parts by weight100 100 100 100 100 component “d” Talc-1 parts by weight 2 2 2 2component “d” Talc-2 parts by weight component “d” WSN-1 parts by weight2 component “d” WSN-2 parts by weight component “d” mica parts by weightnot component “d” CF parts by weight component “e” PTFE parts by weight0.5 0.5 0.5 0.5 0.5 component “f” rubber-1 parts by weight component “f”rubber-2 parts by weight component “f” rubber-3 parts by weight chlorineatom content of molded product ppm 3 3 3 32 30 acrylonitrile monomercontent of molded product ppm 22 5 16 20 23 characteristic impact beforewet heat kgf · cm/cm 52 54 55 50 46 properties resistance valuetreatment after wet heat 42 45 30 37 34 treatment retainability % 81 8355 74 74 apparent before wet heat — 20700 20800 20600 20700 20700molecular weight treatment after wet heat 20500 20600 19900 20400 20400treatment retainability % 99 99 97 99 99 flame retardancy (before wet1.6 mm V-0 V-0 V-0 V-0 V-0 heat treatment) thick item unit Ex. 6 Ex. 7Ex. 8 Ex. 9 composition component “a” PC-1 wt % component “a” PC-2 wt %70 70 70 70 component “a” PC-3 wt % component “b” ABS-1 wt % component“b” ABS-2 wt % 20 20 20 20 component “b” ABS-3 wt % component “b” ABS-4wt % component “c” FR-1 wt % 10 10 10 10 component “c” FR-2 wt % * totalparts by weight 100 100 100 100 component “d” Talc-1 parts by weight 1010 10 component “d” Talc-2 parts by weight component “d” WSN-1 parts byweight component “d” WSN-2 parts by weight component “d” mica parts byweight 2 not component “d” CF parts by weight component “e” PTFE partsby weight 0.5 0.5 0.5 0.5 component “f” rubber-1 parts by weight 4component “f” rubber-2 parts by weight 4 component “f” rubber-3 parts byweight 4 chlorine atom content of molded product ppm 28 25 23 26acrylonitrile monomer content of molded product ppm 23 22 22 25characteristic impact before wet heat kgf · cm/cm 40 34 43 40 propertiesresistance value treatment after wet heat 29 24 35 28 treatmentretainability % 73 71 81 70 apparent before wet heat — 20500 20400 2040020000 molecular weight treatment after wet heat 20200 20000 20000 19500treatment retainability % 99 98 98 98 flame retardancy (before wet heat1.6 mm V-0 V-0 V-0 V-0 treatment) thick Ex.: Example

TABLE 2 item unit Ex. 10 Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 Ex. 16composition component “a” PC-1 wt % component “a” PC-2 wt % 70 70 70 7070 70 70 component “a” PC-3 wt % component “b” ABS-1 wt % component “b”ABS-2 wt % 20 20 20 20 20 20 20 component “b” ABS-3 wt % component “b”ABS-4 wt % component “c” FR-1 wt % component “c” FR-2 wt % 10 10 10 1010 10 10 * total parts by weight 100 100 100 100 100 100 100 component“d” Talc-1 parts by weight 2 10 10 10 component “d” Talc-2 parts byweight 10 component “d” WSN-1 parts by weight 10 component “d” WSN-2parts by weight 10 component “d” mica parts by weight not component “d”CF parts by weight component “e” PTFE parts by weight 0.5 0.5 0.5 0.50.5 0.5 0.5 component “f” rubber-1 parts by weight 4 4 4 component “f”rubber-2 parts by weight 4 4 component “f” rubber-3 parts by weight 4chlorine atom content of molded product ppm 30 22 24 24 21 22 20acrylonitrile monomer content of molded product ppm 20 22 23 25 28 23 22characteristic impact resistance before wet heat kgf · 43 31 41 36 37 1413 properties value treatment cm/cm after wet heat 26 22 34 25 31 12 10treatment retainability % 60 71 83 69 84 86 78 apparent before wet heat— 20300 20300 20300 19800 20300 20300 20100 molecular weight treatmentafter wet heat 19800 19900 19900 19200 19900 19900 19500 treatmentretainability % 98 98 98 97 98 98 97 flame retardancy (before wet 1.6 mmV-0 V-0 V-0 V-0 V-0 V-0 V-0 heat treatment) thick item unit C. Ex. 1 C.Ex. 2 C. Ex. 3 C. Ex. 4 composition component “a” PC-1 wt % component“a” PC-2 wt % 70 77 70 component “a” PC-3 wt % 70 component “b” ABS-1 wt% 20 component “b” ABS-2 wt % 20 23 20 component “b” ABS-3 wt %component “b” ABS-4 wt % component “c” FR-1 wt % 10 10 10 component “c”FR-2 wt % * total parts by weight 100 100 100 100 component “d” Talc-1parts by weight 2 component “d” Talc-2 parts by weight component “d”WSN-1 parts by weight component “d” WSN-2 parts by weight component “d”mica parts by weight not component “d” CF parts by weight 2 component“e” PTFE parts by weight 0.5 0.5 0.5 0.5 component “f” rubber-1 parts byweight component “f” rubber-2 parts by weight component “f” rubber-3parts by weight chlorine atom content of molded product ppm 185 36 33 28acrylonitrile monomer content of molded product ppm 61 22 30 23characteristic impact before wet heat kgf · cm/cm 38 56 63 24 propertiesresistance value treatment after wet heat 8 5 55 2 treatmentretainability % 21 9 87 8 apparent before wet heat — 20600 20700 2380020500 molecular weight treatment after wet heat 18000 16000 23400 16200treatment retainability % 87 77 98 79 flame retardancy (before wet heat1.6 mm V-0 V-0 Not-V V-0 treatment) thick

What is claimed is:
 1. A polycarbonate resin composition which comprises: (A) 40 to 92 wt % of an aromatic polycarbonate resin (component “a”); (B) 5 to 40 wt % of a styrene-based resin (component “b”); (C) 3 to 20 wt % of a phosphate-based flame retardant (component “c”); and (D) 0.1 to 30 parts by weight of a silicate filler (component “d”) based on 100 parts by weight of the total of the components “a”, “b” and “c”, (E) 0.1 to 2 parts by weight of polytetrafluoroethylene (component “e”) having fibril formability based on 100 parts by weight of the total of the components “a”, “b” and “c”; and (F) 1 to 10 parts by weight of a (meth)acrylate-based core-shell graft copolymer (component “f-1”) based on 100 parts by weight of the total of the components “a”, “b” and “c”, wherein the component f-1 is selected from the group (i) a (meth) acrylate-based core-shell graft copolymer (f-1-i) consisting of 40 to 90 wt % of core made from a rubber consisting of 60 to 100 wt % of butadiene and 0 to 40 wt % of styrene and 10 to 60 wt % of a shell made from a polymer or copolymer comprising one or more monomers selected from an acrylic ester, methacrylic ester, aromatic vinyl compound and vinyl cyanide compound and (ii) a (meth)acrylate-based core-shell graft copolymer (f-1-ii) consisting of 40 to 90 wt % of core made from a copolymer rubber consisting of 60 to 90 wt % of an acrylic ester and 10 to 40 wt % of butadiene and 10 to 60 wt % of a shell made from a polymer or copolymer comprising one or more monomers selected from an acrylic ester, methacrylic ester, aromatic vinyl compound and vinyl cyanide compound, and which has a chlorine compound content in terms of chlorine atoms of 100 ppm or less.
 2. The resin composition of claim 1, wherein the component “a” is an aromatic polycarbonate resin obtained by interfacial polymerization.
 3. The resin composition of claim 1, wherein the component “b” is a styrene-based resin containing acrylonitrile as a monomer constituent unit and the resin composition has an acrylonitrile monomer content of 50 ppm or less.
 4. The resin composition of claim 1, wherein the component “b” is a styrene-based resin which contains 20 wt % or more of a styrene-based monomer unit out of all the monomer constituent units.
 5. The resin composition of claim 4, wherein the styrene-based monomer unit is a styrene unit, α-methylstyrene unit or vinyltoluene unit.
 6. The resin composition of claim 1, wherein the component “b” is polystyrene, high-impact polystyrene (HIPS), acrylonitrile.styrene copolymer (AS resin) or acrylonitrile-butadiene-styrene copolymer (ABS resin).
 7. The resin composition of claim 1, wherein the component “b ” is an acrylonitrile.butadiene.styrene copolymer (ABS resin).
 8. The resin composition of claim 1, wherein the component “b” is an acrylonitrile.butadiene.styrene copolymer (ABS resin) obtained by bulk polymerization.
 9. The resin composition of claim 1, wherein the component “c” is a phosphate-based flame retardant represented by the following formula (1):

wherein X is the residual group of an aromatic dihydroxy compound, j, k, l and m are each independently 0 or 1, n is 0 or an integer of 1 to 5, and R₁, R₂, R₃ and R₄ are each independently the residual group of an aromatic monohydroxy compound.
 10. The resin composition of claim 1, wherein the component “d” is a silicate filler which contains a SiO₂ component in an amount of 35 wt % or more.
 11. The resin composition of claim 1, wherein the component “d” is talc, mica or wollastonite.
 12. The resin composition of claim 1 which comprises 50 to 88 wt % of the component “a”, 7 to 35 wt % of the component “b”, 5 to 15 wt % of the component “c” and 0.5 to 20 parts by weight of the component “d” based on 100 parts by weight of the total of the components “a”, “b” and “c”.
 13. The resin composition of claim 1, wherein the content of a chlorine compound is 90 ppm or less based on the resin composition in terms of chlorine atoms.
 14. The resin composition of claim 3, wherein the content of an acrylonitrile monomer is 40 ppm or less based on the resin composition.
 15. The resin composition of claim 1, wherein the component “f-1” is a (meth) acrylate-based core-shell graft copolymer consisting of 40 to 90 wt % of a core made from a rubber consisting of 60 to 100 wt % of butadiene and 0 to 40 wt % of styrene and 10 to 60 wt % of a shell made from a polymer or copolymer of one or more monomers selected from an acrylic ester, methacrylic ester, aromatic vinyl compound and vinyl cyanide compound.
 16. The resin composition of claim 1, wherein the component “f-1” is a (meth)acrylate-based core-shell graft copolymer which consists of 40 to 90 wt % of a core made from a copolymer rubber consisting of an acrylic ester and 10 to 40 wt % of butadiene and 10 to 60 wt % of a shell formed by graft polymerizing at least one selected from an acrylic ester, methacrylic ester, aromatic vinyl compound and vinyl cyanide compound.
 17. The resin composition of claim 1, wherein the component “f-1” is a (meth)acrylate-based core-shell graft copolymer which consists of 50 to 70 wt % of a core made from a rubber latex consisting of 60 to 80 wt % of an acrylic ester and 20 to 40 wt % of butadiene and 30 to 50 wt % of a shell formed by graft polymerizing a mixture of an aromatic vinyl compound and a methacrylic ester and optionally a vinyl cyanide compound in two stages based on 100 wt % of the total of the core and the shell, the amount of the methacrylic ester is 55 to 70 wt % based on 100 wt % of the shell, the amount of the vinyl cyanide compound is 22 to 30 wt % based on 100 wt % of the total of the vinyl cyanide compound and the aromatic vinyl compound when the vinyl cyanide compound is contained, a first graft component is either a mixture of an aromatic vinyl compound and a methacrylic ester or a mixture of an aromatic vinyl compound, a vinyl cyanide compound and a methacrylic ester, a second graft component is a methacrylic ester, the first graft component is contained in an amount of 42 to 70 wt %, and the second graft component is contained in an amount of 30 to 58 wt % based on 100 wt % of the total of shell components.
 18. The resin composition of claim 1 which comprises 50 to 88 wt % of the component “a”, 7 to 35 wt % of the component “b”, 5 to 15 wt % of the component “c”, and 0.5 to 20 parts by weight of the component “d”, 0.1 to 1 part by weight of the component “e” and 2 to 8 parts by weight of the component “f-1” based on 100 parts by weight of the total of the components “a”, “b” and “c”.
 19. A molded article of the resin composition of claim
 1. 20. The molded article of claim 19 which attains V-O rating in an UL standard 94V flammability test.
 21. The molded article of claim 19 which has an impact resistance retainability of 50% or more when it is stored at a temperature of 65° C. and a relative humidity of 85% for 500 hours and an apparent molecular weight retainability of 80% or more. 